The purpose of the ENDO Study (Endometriosis: Natural History, Diagnosis and Outcomes) is to investigate the impact of environmental chemicals and lifestyle in relation to the etiology of gynecologic diseases, particularly endometriosis. The study is primarily interested in persistent organic pollutants (i.e., polychlorinated biphenyls, polybrominated diphenyl ethers, perfluorinated chemicals, and heavy metals) and lifestyle behaviors. These persistent compounds are known to resist degradation;their structural composition allows them to bioaccumulate and biomagnify within the environment. Under a matched-exposure cohort design, two cohorts of women are being recruited -- those undergoing surgery for gynecologic complaints and those undergoing magnetic resonance imaging (MRI) to determine whether they have asymptomatic endometriosis. Approximately 850 women undergoing laparoscopy or laparotomy will be recruited along with approximately 200 women undergoing MRIs from the geographic areas served by the clinical facilities with ENDO study sites . Participating women complete baseline interviews, anthropometric assessment and consent to the provision of blood, urine and operative biologic specimens. This is the first population-based study that is aimed at determining the relation between these classes of environmental chemicals and the presence of endometriosis and its severity. Another key feature of the study is the anthropometric assessment. This design feature will allow the investigators to determine if current and former body shape is associated with endometriosis or other gynecologic diseases as recently speculated supporting a possible in utero origin of endometriosis. If women with endometriosis are found to be leaner throughout their lives in comparison to women without endometriosis, this observation may suggest that in utero exposures affecting body habitas reprogram the female fetus for subsequent gynecologic diseases such as endometriosis.